Acupuncture guide tubes are widely used in the practice of acupuncture to minimize discomfort during needle insertion. The guide tube allows quick insertion of an acupuncture needle through the epidermis. An example of a guide tube is the one shown in U.S. Pat. No. 5,792,171 issued in 1998 to Burdenko, et al. Fast puncturing of the patient's skin is important for pain-free insertion. There is typically 3-5 mm clearance between the upper end of the guide tube and the top of the handle of an acupuncture needle, which protrudes above the tube. The practitioner taps on the handle of the needle downward with his/her index finger while supporting the tube with the other hand. The needle, which has been resting on the surface of the patient's skin prior to insertion, is now inserted 3-5 mm through the skin into the acupuncture point. The guide tube has a diameter, which is bigger than the diameter of the handle of the acupuncture needle. This allows the removal of the guide tube after the insertion. On one hand, the relatively big diameter of the tube, in comparison with the shaft of the needle, provides more comfort for the patient by creating mild pressure around the acupuncture point and by providing firmness to the skin around that point. This feature is important for fast, pain-free insertion. On the other hand, the relatively big diameter of the tube compromises the precision of the insertion. This is because the tip of the needle is rarely in the center of the bottom opening of the tube prior to insertion, but at the sides, leaning against the inside tubular wall. The needle then tends to take diagonal orientation in respect to the tubular longitudinal axis. The tip of the needle, which rests on the skin, is at the bottom tubular wall opposite to the handle.
The practitioner is often unaware about an exact position of the needle. Hence, the angle at which the needle is inserted into the point is unpredictable. Furthermore, when the practitioner attempts to insert a needle at sharp angles, such as on the face or head of the patient, the acupuncture needle tends to slide downward, out of the guide tube. This condition is shown in FIG. 1, which illustrates the positions of a needle guide tube 10 and an acupuncture needle 13. As can be seen from FIG. 1, when the needle 13 is inserted at a sharp angle to the surface of the skin S, a very little clearance C is left between the upper portion of the tube and the handle H of the needle 13. This makes the regular insertion technique very uncomfortable, if not impossible. Also, the clearance C is too small for full penetration of the tip of the needle through the epidermis. As a result, the patient may feel more pain than is necessary.
There are two reasons that contribute to the reduction of this clearance C on top. One reason has to do with the thickness T of the tubular wall. The acupuncture needle 13 has to go a little forward and downward, over the small threshold formed by the bottom edge E of the guide tube 10, to touch the skin S. The other reason has to do with the fact that in the inclined position (angular insertion) shown in FIG. 1, both the tip F of the needle 13 and the handle H of the needle are now against the same tubular wall. This contributes to the additional "slip out" of the needle at the skin S. It would be better, if the handle of the needle stayed at the opposite wall (diagonally), thus shortening the distance that the needle has to travel to reach the skin. But it is often hard to maintain this position of the handle during angular insertions because of the pressing of the handle H of the needle 13 against upper wall with index finger: there is not enough space between the handle H and the skin S. Sometimes, acupuncture insertions have to be performed against gravity. Needling of the points at the cervical spine with the patient in a sitting position is just one example of this. The acupuncture needle tends to slide out of the guide tube during such insertions, and regular insertion technique becomes impossible.